Back to EveryPatent.com
United States Patent |
6,004,497
|
Bisognin
,   et al.
|
December 21, 1999
|
Process for covering a plastics part with a foil cut during the process
Abstract
A process for substantially covering with at least one non-rigid decorative
foil a visible face of a support part of plastic material, so as to obtain
a finished part including a decorative inset, including the steps of a)
inserting into the mould the foil having a decorative area with the foil
having a decorative area, intended to form the inset, and a further area,
b) closing the mould at least partially by moving the two mould parts
together such that the foil creates a continuous separation of the
moulding cavity into a first space and a second space, c) inside the
moulding cavity, cutting at least one aperture in the foil at the location
of the further area, such that the first and second spaces of the cavity
are placed in fluid communication by the at least one aperture which
henceforth interrupts the separation between these two spaces so as to
enable the plastic material to pass through the at least one aperture,
leaving a cut end of the foil in the moulding cavity, d) before and/or
after steps b) and/or c), introducing plastics material into the mould
cavity, and e) after step c), distributing the plastic material in the
moulding cavity by passing it through the at least one aperture in order
to obtain the decorative support part locally covered by the inset,
wherein the cut end of the foil is immersed in the plastic material.
Inventors:
|
Bisognin; Julien (Andeville, FR);
Baudouin; Ivan (Paris, FR);
Trillat; Sebastien (Poissy, FR)
|
Assignee:
|
Allibert Industrie (societe en nom collectif) (FR)
|
Appl. No.:
|
853912 |
Filed:
|
May 5, 1997 |
Foreign Application Priority Data
| May 10, 1996[FR] | 96 05858 |
| Apr 18, 1997[EP] | 97 400 879 |
Current U.S. Class: |
264/153; 264/156; 264/266; 264/273; 264/275; 425/120; 425/129.1 |
Intern'l Class: |
B29C 045/14 |
Field of Search: |
264/154,273,266,163,155,328.12,156,40.7,275
425/112,120,553,129.1,127
|
References Cited
U.S. Patent Documents
3184096 | May., 1965 | Cheeley.
| |
3651191 | Mar., 1972 | Glatt et al. | 264/153.
|
5019313 | May., 1991 | Warburton | 264/154.
|
5147591 | Sep., 1992 | Yoshida | 264/163.
|
5629029 | May., 1997 | Souder et al. | 425/112.
|
Foreign Patent Documents |
0428765 | Dec., 1972 | AU.
| |
0043174 | Jan., 1982 | EP.
| |
0491682 | Jun., 1992 | EP.
| |
0636464 | Feb., 1995 | EP.
| |
0684120 | Nov., 1995 | EP.
| |
0724942 | Aug., 1996 | EP.
| |
2271956 | May., 1994 | GB.
| |
Primary Examiner: Silbaugh; Jan H.
Assistant Examiner: Lee; Edmund H.
Attorney, Agent or Firm: Rothwell, Figg, Ernst & Kurz
Claims
We claim:
1. Process for substantially covering a visible face of a support part of
plastic material with at least one non-rigid decorative foil, in a mould
substantially comprising first and second mould parts which form a
moulding cavity therebetween, to produce a decorative support part having
a decorative inset, the process comprising the following steps:
a) inserting into the mould the foil which comprises a decorative area,
intended to form the inset, and a further area;
b) closing the mould at least partially by moving the two mould parts
together such that the foil creates a continuous separation of the
moulding cavity into a first space and a second space;
c) inside the moulding cavity, cutting the foil discontinuously to form
discrete apertures therein at the location of the further area, whereby
the first and second spaces of the cavity are placed in fluid
communication by the apertures which henceforth interrupts the separation
between said first and second spaces so as to enable the plastic material
to pass through the apertures, leaving a cut end of the foil in the
moulding cavity;
d) before and/or after steps b) and/or c), introducing plastic material
into the moulding cavity; and
e) after step c), distributing the plastic material in the moulding cavity
by passing the plastic material through the apertures in order to produce
the decorative support part locally covered by the inset with the cut end
of the foil immersed in and immobilized by the plastic material.
2. Process according to claim 1, wherein during step d), the plastic
material is injected under pressure into the moulding cavity.
3. Process according to claim 2, wherein:
during step d) a first injection stage is carried out in which plastic
material is injected under pressure at a side of the decorative area, such
that the decorative area of the foil is brought to bear against one of the
mould parts intended to receive the foil; and
during step e) the first injection stage is continued so that the plastic
material is made to pass through the apertures, and a second injection
stage is carried out in which plastic material is injected outside the
decorative area and contacts the material of the first injection stage.
4. Process according to claim 3, wherein the side of the decorative area
where the plastic material is injected is almost completely coated with
plastic material before the foil is cut out during step c).
5. Process according to claim 3, wherein after step c), the injection of
material at the decorative area and outside the decorative area is
controlled such that, during the first and second injection stages,
opposing forces are applied by material on either side of the further
area, thus preventing showing of the further area of the foil on the
visible face of the finished part.
6. Process according to claim 1, wherein:
The first mould part comprises at least two components;
a recess is formed in the foil; and
during step a), an area of the foil defining the periphery of the recess is
introduced between the two components of the first mould part where the
foil is held.
7. Process according to claim 1, wherein:
the first mould part comprises at least two components;
during step a), an area of the foil outside the decorative area is
introduced between the two components of the first mould part; and
during step b), the mould is only closed partially, the mould being
completely closed during step c) and producing the apertures in the foil
by exerting pressure between the first and second components of the first
mould part.
8. Process according to claim 1, wherein during step b), the foil is placed
between two components of a punch device formed on the first mould part
and the second mould part, and, during step c), a punch aperture is formed
instantaneously through the foil by bringing the two components of the
punch device into contact with each other.
9. Process according to claim 8, wherein the two components of the punch
device are held in contact with each other until after step e).
10. Process according to claim 1, wherein the first space is located at the
decorative area; and in that after step c), there is created in the
immediate vicinity of the apertures in the foil an eddying effect or the
flow of material injected into the first space is held back against the
natural movement of the flow of material injected towards the periphery of
the second space in order to prevent the further area of the foil showing
on the visible face.
11. Process according to claim 1, wherein after step c), the foil-retention
area is held completely such that movement thereof is prevented.
12. Process for substantially covering a visible face of a support part of
plastic material with at least one non-rigid decorative foil, in a mould
substantially comprising first and second mould parts which form a
moulding cavity therebetween, to produce a decorative support part having
a decorative inset, the process comprising the following steps:
a) inserting into the mould the foil which comprises a decorative area,
intended to form the inset, and a further area;
b) closing the mould at least partially by moving the two mould parts
together such that the foil creates a continuous separation of the
moulding cavity into a first space and a second space;
c) inside the moulding cavity, cutting the foil discontinuously to form
discrete apertures therein at the location of the further area, whereby
the first and second spaces of the cavity are placed in fluid
communication by the apertures which henceforth interrupts the separation
between said first and second spaces so as to enable the plastic material
to pass through the apertures, leaving a cut end of the foil in the
moulding cavity;
d) before and/or after steps b) and/or c), introducing plastic material
into the moulding cavity; and
e) after step c), distributing the plastic material in the moulding cavity
by passing the plastic material through the apertures in order to produce
the decorative support part locally covered by the inset,
wherein from step b) until after step e), the foil is held at least
partially on the mould in a foil-retention area outside the decorative
area until a cut end of the foil is immersed in and immobilized by the
plastic material.
13. Process for substantially covering a visible face of a support part of
plastic material with at least one non-rigid decorative foil, in a mould
substantially comprising first and second mould parts which form a
moulding cavity therebetween, to produce a decorative support part having
a decorative inset, the process comprising the following steps:
a) inserting into the mould the foil which comprises a decorative area,
intended to form the inset, and a further area;
b) closing the mould at least partially by moving the two mould parts
together such that the foil creates a continuous separation of the
moulding cavity into a first space and a second space;
c) inside the moulding cavity, cutting the foil to form at least one
aperture therein at the location of the further area, whereby the first
and second spaces of the cavity are placed in fluid communication by the
at least one aperture which henceforth interrupts the separation between
said first and second spaces so as to enable the plastic material to pass
through the at least one aperture, leaving a cut end of the foil in the
moulding cavity;
d) before and/or after steps b) and/or c), introducing plastic material
into the moulding cavity; and
e) after step c), distributing the plastic material in the moulding cavity
by passing the plastic material through the at least one aperture in order
to produce the decorative support part locally covered by the inset,
wherein
during step d), a first injection stage is carried out in which plastic
material is injected under pressure at the decorative area, such that the
decorative area of the foil is brought to bear against one of the mould
parts intended to receive the decorative area; and
during step e), the first injection stage is continued so that the plastic
material is made to pass through the at least one aperture and a second
injection stage is carried out in which plastic material is injected under
pressure outside the decorative area and contacts the material of the
first injection stage.
14. Process for substantially covering a visible face of a support part of
plastic material with at least one non-rigid decorative foil, in a mould
substantially comprising a first and second part which form a moulding
cavity therebetween, so as to obtain a finished part comprising a
decorative inset, the process comprising the following steps:
a) inserting into the mould the foil which comprises a decorative area,
intended to form the inset, and a further area;
b) closing the mould at least partially by moving the two mould parts
together such that the foil creates a continuous separation of the
moulding cavity into a first space and a second space;
c) inside the moulding cavity, cutting at least one aperture in the foil at
the location of the further area, such that the first and second spaces of
the cavity are placed in fluid communication by the at least one aperture
which henceforth interrupts the separation between these two spaces so as
to enable the plastic material to pass through the at least one aperture,
leaving a cut end of the foil in the moulding cavity;
d) before and/or after steps b) and/or c), introducing plastic material
into the moulding cavity by injecting the plastic material into the
moulding cavity under pressure; and
e) after step c), distributing the plastic material in the moulding cavity
by passing the plastic material through the at least one aperture in order
to obtain the decorative support part locally covered by the inset,
wherein the cut end of the foil is immersed in the plastic material,
wherein during step d) a first injection stage is carried out in which
plastic material is injected under pressure at a side of the decorative
area such that the decorative area of the foil is brought to bear against
one of the mould parts intended to receive the foil; and
wherein during step e) the first injection stage is continued so that the
plastic material is made to pass through the at least one aperture, and a
second injection stage is carried out in which plastic material is
injected outside the decorative area and contacts the material of the
first injection stage.
15. Process according to claim 14, wherein the side of the decorative area
where the plastic material is injected is almost completely coated with
plastic material before the foil is cut out during step c).
16. Process according to claim 14, wherein after step c), the injection of
material at the decorative area and outside the decorative area is
controlled such that, during the first and second injection stages,
opposing forces are applied by material on either side of the further
area, thus preventing showing of the further area of the foil on the
visible face of the finished part.
17. Process according to claim 14, wherein:
the first mould part comprises at least two components;
a recess is formed in the foil; and
during step a), an area of the foil defining the periphery of the recess is
introduced between the two components of the first mould part where the
foil is held.
18. Process according to claim 14, wherein:
the first mould part comprises at least two components;
during step a), an area of the foil outside the decorative area is
introduced between the two components of the first mould part; and
during step b), the mould is only closed partially, the mould being
completely closed during step c) and producing the at least one aperture
in the foil by exerting pressure between the first and second components
of the first mould part.
19. Process according to claim 14, wherein during step b), the foil is
placed between two components of a punch device formed on the first mould
part and the second mould part, and, during step c), a punch aperture is
formed instantaneously through the foil by bringing the two components of
the punch device into contact with each other.
20. Process according to claim 19, wherein the two components of the punch
device are held in contact with each other until after step e).
21. Process according to claim 14, wherein the first space is located at
the decorative area; and in that after step c), there is created in the
immediate vicinity of the aperture in the foil an eddying effect or the
flow of material injected into the first space is held back against the
natural movement of the flow of material injected towards the periphery of
the second space in order to prevent the further area of the foil showing
on the visible face.
22. Process according to claim 16, characterized in that before step c),
the foil is held on the mould in a foil-retention area outside the
decorative area and the foil is cut continuously during step c) in order
to separate the decorative area and the retention area.
23. Process according to claim 14, characterized in that as from step b),
the foil is held on the mould in a foil-retention area outside the
decorative area and, during step c), the foil is cut out discontinuously
such that the foil is held at least partially until after step e).
24. Process according to claim 19, wherein before step c) the foil is held
on the mould in a foil-retention area outside the decorative area and the
foil is cut continuously during step c) in order to separate the
decorative area and the retention area.
Description
The invention concerns a process for substantially covering with at least
one non-rigid decorative foil (or sheet) a visible face of a support part
of plastics material(s) in a mould substantially comprising a first and a
second part which form a moulding cavity therebetween.
What is to be understood by a non-rigid foil or sheet is a flexible
material (PVC, fabric or non-woven, etc.) which can comprise a layer of
foam or the like but which is deformable. The foil may be shaped solely in
the mould during the process in which the entire part is moulded or it may
already have been pre-shaped beforehand such that, before the present
process is implemented, the foil has an initial shape similar to that of
the part of the mould with which it is to come into contact.
More particularly, the invention concerns the production of a finished part
comprising a decorative inset which covers only a portion of the visible
face. The problems inherent in this type of production generally consist
in positioning the foil correctly, leaving only a specific portion of the
foil showing on the finished part whilst permitting satisfactory cohesion
between the portion covered by the decorative foil and the portion which
is not covered.
In the following the visible portion of the foil on the finished part and
forming part of the visible face will be known as the "inset". The portion
of the support part not covered by the foil will be said to be "not
moulded over" or "non-covered", whilst the portion located "below" the
inset will be said to be "moulded over" or "covered".
In order to overcome the above problems, the invention proposes a process
comprising the following steps:
a) inserting into the mould the foil which comprises a decorative area,
intended to form the inset, and a further area;
b) closing the mould at least partially by moving its two parts together
such that the foil creates a continuous separation of the moulding cavity
into a first space and a second space;
c) cutting out inside the moulding cavity at least one aperture in the foil
at the location of the further area, such that the first and second spaces
of the cavity are placed in fluid communication by this aperture which
henceforth interrupts the separation between these two spaces so as to
enable the material to pass through this aperture;
d) before and/or after steps b) and/or c), introducing plastics material
into the mould cavity;
e) after step c), distributing the material in the moulding cavity by
passing it through the aperture in order to obtain the decorative support
part locally covered by the inset;
f) cooling the part; and
g) opening the mould and ejecting the finished part.
In this way, the problems posed by the wicking effect and the cohesion
between the portions moulded over and not moulded over are largely
overcome. The number and arrangement of the passages for the material
passing through the foil structure can be controlled since they correspond
to the locations where the cut-out is made. Moreover, since the cut-out in
the foil is made in the moulding cavity and places the two spaces in fluid
communication as soon as it is produced, the aperture can be positioned
precisely relative to the mould.
It should be specified that the phenomenon whereby humidity spreads by
capillary action along the foil, in particular along the fibres when the
foil is fibre-based, is generally known as the "wicking effect".
Although EP-A-0 724 942 describes a process which, in order to pass
material through the foil, proposes cutting out the foil in the vicinity
of the moulding cavity using a blade fixed to one of the mould parts, no
aperture placing the two spaces in communication is produced in the cavity
as soon as the cut-out is made.
On the other hand, EP-A-0 684 120 proposes stretching the foil over
cavities in order to bring about cohesion between the covered portion and
the non-covered portion. As long as the foil is not cut out, the structure
of this foil bursts under the pressure of the material injected into the
moulding cavity.
However, when the material starts to pass through the structure of the foil
at given locations, a drop in pressure is noted or at least the pressure
reaches a stage such that the passages remain localized. Consequently, the
material passages cannot increase or at least cannot exist in a
sufficiently large number. Therefore this solution proves complex,
allowing only limited cohesion between the covered and non-covered
portions and only reducing the "wicking effect" to a slight degree.
It should be noted that the invention aims to overcome the above problems,
irrespective of the relative position of the covered and the non-covered
portions. In particular, these two parts may be adjacent or the covered
portion may surround the non-covered portion or vice versa. They may also
be arranged such that their configuration is a combination of both these
possibilities.
Furthermore, in order that the finished part has a satisfactory appearance,
in particular the non-covered portion thereof, the invention proposes that
during step d) and preferably also during step e) the plastics material is
injected under pressure into the moulding cavity.
The finished part is then obtained directly without having to subject the
part to an additional moulding operation in order to ensure that the
non-covered portion has a satisfactory appearance.
In order to reduce the risk of blemishes on the finished part, the
invention even advantageously proposes that:
during step d) a first injection stage be carried out in which the plastics
material is injected under pressure opposite one side of the decorative
area, such that the decorative area of the foil is brought to bear against
one of the mould parts intended to receive it; and
during step e) the first injection stage be continued so that the plastics
material is made to pass through the apertures, and a further pressurized
injection process be carried out in which plastics material is injected
outside the decorative area.
Injecting the material first "below" (that is, opposite) the decorative
area enables the foil to be positioned whilst shaping it in the moulding
cavity. The second injection stage enables the flow of material resulting
from the first injection stage to continue, which improves the appearance
of the non-covered portion and enables a larger non-covered portion to be
produced. Moreover, the second injection stage can be carried out at a
higher pressure (preferably at between 20 and 40 MPa, depending on the
material) in this non-covered portion in which the inset is not provided,
whilst the pressure of the first injection stage is more moderate
(preferably between a few MPa and 20 MPa).
According to a further feature of the invention, on the injection side, the
decorative area is almost completely coated with plastics material before
the foil is cut out during step c). Consequently, before cutting out, the
decorative area can be held by means of the further area, in particular
its tension can be controlled, so enabling the decorative area to be
shaped satisfactorily. The almost complete coating of the decorative area
enables this shape to be set, so preventing the decorative area of the
foil deforming after the cutting-out process.
In order to produce a non-covered portion surrounded by a covered portion,
the invention proposes that:
the first mould part comprise at least two components;
a recess (hole with a closed contour) be formed in the foil; and
during step a), an area of the foil defining the periphery of this recess
be introduced between the two components of the first mould part where the
foil is held.
In order to further improve the part production process, in particular the
positioning of the aperture in the mould cavity, the invention
advantageously proposes that:
the first mould part comprise at least two components;
during step a), an area of the foil outside the decorative area be
introduced between the two components of the first mould part; and that
during step b), the mould be closed only partially, the mould being
completely closed during step c) and producing the cut-out in the foil by
exerting pressure between the first and second components of the first
mould part.
Therefore the aperture is formed only when the shaping of the foil and in
particular the shaping of the decorative area during closure of the mould
is completed. From that moment, the risk of the aperture's moving in the
moulding cavity and being located on the visible face is considerably
reduced.
In order to further improve the formation of the aperture in the foil, the
invention proposes that, during step b), the foil be placed between two
components of a punch device and, during step c), an aperture be
instantaneously formed through the foil by bringing the two components of
the punch device into contact with each other.
The aperture is thus produced easily and positioned precisely in a reliable
and rapid manner, which shortens the part production time.
In order to increase the diversity of the parts produced, the invention
proposes that the two components of the punch device be held in contact
with each other until step f). In this way, a finished part is produced
which has a passage of which the shape can be determined by this punch.
In order to prevent parts of the foil showing on the visible face of the
finished part at the portion which has not been moulded over, the
invention proposes that, after step c), the injection of material opposite
the decorative area and outside this decorative area be controlled such
that, during the first and second injection stages, opposing forces be
applied by material on either side of the further area, thus preventing
its showing on the visible face of the finished part. By controlling the
flow(s) of material, the aperture can be prevented from moving in the
direction of the visible face.
As a further or alternative solution, the invention proposes that, after
step c), an eddying effect be created in the immediate vicinity of the
aperture cut out in the foil or the flow of material injected into the
first space be held back against its natural movement towards the
periphery of the second space, in order to prevent the further area of the
foil showing on the visible face.
The above two solutions are all the more advantageous since, in order to
prevent a wicking effect, as the foil is held on the mould in a
foil-retention area outside the decorative area before step c), the foil
is cut out continuously during step c) in order to separate the decorative
area and the retention area. In fact, if these two areas are totally
separate, no wicking effect at all is possible.
If the problem of the wicking effect is not of primary importance, the
invention proposes that, as from step b), the foil be held on the mould in
a foil-retention area outside the decorative area and, during step c), the
foil be cut out discontinuously such that the foil is held at least until
step f). In this way, the movements of the foil are better controlled and
hence the quality of the appearance of the inset on the finished part is
improved. This solution further prevents the cut-out appearing on the
visible face.
In particular, according to an advantageous feature of the invention, after
step c), the foil-retention area is held completely such that movement
thereof is prevented.
The invention further concerns a finished part obtained by the above
process. According to the invention, the finished part comprises a covered
portion, in which a non-rigid decorative foil covers a visible face of a
support part of plastics material, and a non-covered portion in which
there is no decorative foil on the visible face, the covered portion
completely surrounding the non-covered portion.
Together with the configurations already known, this configuration enables
parts to be produced which have almost all the relative arrangements
possible between the covered and non-covered portions.
In the following the invention will be explained in further detail with
reference to the attached drawings, in which:
FIG. 1 shows in section a mould according to the invention during a first
step of the process;
FIG. 2 shows in section a mould according to the invention during a second
step of the process;
FIG. 3 shows in section a mould according to the invention during a third
step of the process;
FIG. 4 shows on a larger scale the detail marked IV in FIG. 3, during a
step preceding that shown in FIG. 3;
FIG. 5 shows on the same scale the detail marked IV in FIG. 3, during the
same step as shown in FIG. 3;
FIG. 6 shows, still on the same scale, the detail marked IV in FIG. 3,
during a subsequent step of the process;
FIG. 7 is a view in section along the line VII--VII of FIG. 6;
FIGS. 8 and 9 show variant embodiments of the mould in the detail part
marked IV in FIG. 3;
FIG. 10 is a plan view of the foil used in FIGS. 11 to 13;
FIG. 11 shows a variant of the mould during a first step of the process;
FIG. 12 shows the mould of FIG. 11 during a second step of the process;
FIG. 13 shows on a larger scale the detail marked XIII in FIG. 12, during a
third step of the process;
FIGS. 14 and 15 illustrate a further variant of the mould during two
successive steps of the process;
FIG. 16 illustrates on a larger scale the detail marked XVI in FIG. 15,
during a third step of the process;
FIGS. 17 to 22 show plan views of different parts obtained by the process
of the invention.
FIGS. 1 to 3 illustrate a mould 4 comprising a first movable part 4a and a
second part consisting of a fixed part 4b and a window 4c (frame-like
block). In this case the window 4c is connected to the fixed part 4b by
actuators 5. However, the window can alternatively be structurally
connected to the movable part 4a of the mould by means of actuators or the
like.
In FIG. 1 the mould 4 is in the open position; the movable part 4a and the
fixed part 4b are far apart from each other and the window is in the
extended position, not bearing on the fixed part.
A foil or sheet 2 is positioned between the fixed part 4b and the window 4c
by a first arm 6a of a robot 6. The foil is then secured on pins 8 at the
top or by any other holding means. The remainder of the foil is then
positioned by gravity, the cutting plane being vertical.
In FIG. 2 the window is partially closed. There is still a spacing d
between the window 4c and the fixed part 4b of the mould. The
foil-retention means, consisting in particular of the pins 8 and the
pinching of the foil between the window 4c and the fixed part 4b of the
mould, are then active, that is, they hold a peripheral marginal retention
area 2a of the foil 2. However, since the window is only closed partially,
the foil is not completely immobilized, that is, it can slide relative to
the retention means. The tension of the foil 2 is thus controlled.
Thermoplastics material 1, intended to serve as a support for the finished
part, is then injected from the fixed part 4b of the mould into an inner
space 16 located below the foil 2. As the space 16 fills, the mould is
progressively closed by bringing the two parts 4a, 4b together such that
the material 1 is injected and compressed.
At the end of the injection-compression phase, the movable part 4a of the
mould bears against the window 4c. FIG. 4 shows that the mould 4, and in
particular the window 4c, is not completely closed at this stage--the
spacing d still separates the window 4c from the fixed part 4b. A space 20
remains around the foil 2, between the window 4c and the fixed part 4b.
Thus, although the foil is held, controlled sliding thereof is still
possible between the window and the part 4b.
When the space 16 has been completely or almost completely filled, as shown
in FIG. 5, a central area 2c of the foil 2, which is to appear on the
visible face of the finished part in order to constitute the inset there,
is applied by the thermoplastics material 1 against the movable part 4a
located opposite the first space 16. The central area 2c is surrounded by
a connection area 2b which is in turn surrounded by the peripheral
retention area 2a, the whole constituting the foil 2.
The mould has a cavity 17 comprising the space 16 and an outer space 18
surrounding the space 16. In this case these two spaces are separated by
the connection area 2b of the decorative foil.
It is possible to detect the filling of the space 16 by measuring the
volume of material injected or the opening of the mould or by using event
sensors (pressure, heat flow, temperature or optical sensors or the like).
When the space 16 is almost full, the order is given for the mould to be
closed and the fixed part 4b and movable part 4a then move towards each
other.
In FIGS. 3 and 5 the mould is completely closed, the moving together of the
parts 4a and 4b having brought about the closure of the window 4c which is
now in contact with the fixed part 4b. The shapes of the mould parts and
of the window 4c are designed such that, during its movement towards the
fixed part 4b, the movable part 4a comes to bear against the window 4c so
as to push it until it comes into contact with the part 4b.
The window 4c comprises a projecting portion 12 forming a sharp edge in the
manner of a "parrot's beak". At the boundary between the connection area
2b and the peripheral retention area 2a, this parrot's beak cuts out the
foil 2 under the effect of the pressure of the complete closure of the
mould 4. It is important that the foil 2 be cut out at least at the
connection area 2b, that is, within or at the boundary of the moulding
cavity in order to place the spaces 16 and 18 in communication.
In FIGS. 6 and 7 the foil 2 is only cut out partially. The connection area
2b, and hence the central area, are thus held since they are still
connected by sections 2d to the retention area 2a. Total closure of the
mould prevents the retention area 2a between the window 4c and the fixed
part 4b of the mould from sliding. Therefore there is no risk of the
connection area 2b being applied against the movable part 4a of the mould
and appearing on the visible face of the finished part.
As concerns the cut-outs 2e they enable the space 16 and the outer space 18
to be placed in communication as soon as they are produced. The flow of
material can thus continue from the space 16, covered by the inset, to the
space 18 where the visible portion of the finished part will not be
covered.
The material 1 is progressively injected via nozzles 10a, 10b, 10c, 10d and
10e from the centre of the central area 2c to the periphery thereof, then
to the periphery of the non-covered portion of the part when the cut-outs
2e have been made in the foil. The space 16 is thus filled first by
nozzles 10a then 10b and 10c, whilst the space 18 is subsequently filled
using nozzles 10d and 10e.
This sequential injection process is brought about using the
above-mentioned sensors, such as in particular event sensors, the order
for material to be injected from a nozzle being given when the front of
injected material arrives thereat. This front of material is controlled
such that it moves continuously towards the periphery of the cavity 17, so
preventing visible seams on the finished part.
Moreover, the injection pressure of the material 1 is advantageously higher
at the end of the filling step, in particular when the material continues
to flow only out of the nozzles 10d and 10e located in the space 18. In
this way, the quality of the appearance of the non-covered face is
improved--the higher the pressure, the better the quality of the
appearance of the finished part and in particular the less visible the
seams--without the risk of impairing the inset by too high an injection
pressure.
FIG. 1 shows the finished part 40 partially covered on its visible face 44
by the foil 2 and held by a second arm 6b of the robot 6. Its support 42,
consisting of the hardened thermoplastics material 1, having hardened, the
finished part 40 is removed from the mould by moving apart the two mould
parts. This figure does not show the means for the final cutting of the
foil 2 enabling the retention area 2a to be separated from the finished
part 40.
FIG. 8 shows a variant in which the connection area 2b has been completely
cut off by the "parrot's beak" 22. (However, this cut-out may be partial,
as shown in FIGS. 6 and 7).
The risk of the central zone 2c moving is reduced owing to the fact that,
since the material 1 is first injected below the inset--in particular by a
sequential injection process--the material has already cooled in this area
and "hardened" when the foil is cut, that is essentially when the front of
material arrives in the space 18. This helps to hold the inset and prevent
its moving.
On the other hand, since the connection area 2b is no longer held by the
retention area 2a, it has to be prevented from being able to appear on the
visible face of the finished part. To this end, the movable part 14a of
the mould has a rib 28 against which the edge of the central area 2c abuts
in the space 16, this rib creating a step 30 in the space 18. The boundary
between the spaces 16 and 18 is then defined by an imaginary line
connecting the rib 28 and the parrot's beak 22.
The fixed part 4b also has a step 26, such that the space 18 has a widened
area 34 delimited by the steps 26 and 30. The length of the widened area
34 is slightly longer than that of the foil-connection area 2b.
By virtue thereof, the connection area 2b is prevented from moving to the
visible face, for two reasons:
Firstly, the material 1 coming from the space 16 abuts the step 26 and
assumes an eddying movement illustrated by the arrow 32 such that the
material passes behind the connection area 2b so that it surrounds and
immerses this area, up to the rib 28. This rib 28 prevents the material 1
penetrating between the inset 2c and the movable part 14a of the mould.
Secondly, if the material 1 is injected into the space 18 outside the
widened area 34, as soon as the mould is completely closed (that is, as
soon as the foil is cut), the flow of material from the space 18 will
progress in the direction of the arrow 36 as far as the step 30 and be
positioned between the movable part 14a of the mould and the connection
area 2b. This connection area 2b will be immersed in the plastics
material, between the flows of material 1 from the spaces 16 and 18. The
seam line created by the meeting of the two flows is not a hindrance here
since it does not appear on the visible face.
Moreover, the flows of material from the spaces 16 and 18 thus apply
opposing forces to the foil. The stresses to which the foil is subject and
which tend to move it towards the visible face are thus reduced.
FIG. 9 shows a secondary cavity 38 communicating with the general moulding
cavity and formed in the fixed part 24b of the mould. The movable part of
the mould 24a and the window 24c can be those illustrated previously. The
foil can be cut out partially or completely.
This cavity 38 is formed at the edge of the space 16 and acts as a material
"feeder", that is, an "overflow" reservoir. When the material 1 is
injected into the space 16, the material spreads about the injection
points 10a, 10b, 10c. In this way, the connection area 2b risks being
impregnated with material at given locations before others. Therefore it
is necessary to wait for the central area 2c to be almost completely
coated with thermoplastics material before cutting the foil. The
accumulation of material then causes a rise in the pressure of the
material, causing material to pass through the connection area.
The secondary cavity 38 creates a clearance area for the material whilst
waiting for the foil to be cut and so avoids material passing through the
foil by preventing compression of the material as a result of its
accumulating in part of the injection space. It thus enables the different
filling levels of the space 16 to be balanced. At the end of the injection
stage, the cavity 38 is completely filled with material.
FIGS. 10 to 13 illustrate a variant enabling a portion which is not covered
by a decorative foil and is completely surrounded by a portion covered by
a decorative foil to be produced. In these figures parts corresponding to
those in the preceding figures are denoted by a reference number increased
by 50.
In FIG. 11 the mould 54 essentially differs from the mould 4 only in that
the fixed part 54b comprises a movable core 54d actuated by an actuator
(not shown). The robot 56 introduces a foil 53 into the mould between the
movable part 54a and the window 54c.
This foil 53 is illustrated in greater detail in FIG. 10. It has a recess
53a such that it forms a sort of collar between an inner edge 53b,
delimiting the recess, and an outer edge 53c. About the recess the foil 53
comprises indents 53d which extend radially into the foil from the edge
53b.
The robot secures the foil at the top on the pins 58. The core 54d is then
inserted through the recess 53a in the foil 53. The core 54d is then
closed by moving it towards the fixed part 54b of the mould, such that an
internal peripheral retention area 53f and in particular the inner edge
53a of the foil is disposed between the core 54d and the fixed part of the
mould 54b.
As FIG. 12 illustrates, during closure of the core 54d, the internal area
53f is held relative to the core 54d, the internal area 53f then moves,
substantially following the movement of the core 54d. Thus the indents 53d
are located between the core 54d and the fixed part 54b of the mould.
Consequently, the indents 53d facilitate positioning of the foil,
preventing the foil 53 puckering when it is placed between the core 54d
and the fixed part 54b, and risking showing on the finished part.
The window 54c is closed as described above in conjunction with the window
4c, substantially at the same time as the core 54d is closed. An outer
peripheral retention area 53e and in particular the outer edge 53c are
disposed between the window 54c and the fixed part 54b. The external area
53e can be held to a greater or lesser extent relative to the window 54c
as described in conjunction with the core 54d, in order to apply the
desired tension to the foil 53.
The core 54d is then only closed partially; as with the window 54c, there
is a spacing d' (substantially equal to d) between the core and the fixed
part 54b.
The moulding cavity 67 thus has three spaces 66, 68 and 69 continuously
separated by the foil 53, as shown in FIG. 13. The plastics material 51 is
then injected into the space 66, bringing a decorative area 53g of the
foil into abutment against the movable part 54a of the mould. It will be
appreciated that the situation in the areas marked A and D corresponds to
what was described previously in conjunction with the detail IV. It will
also be appreciated that the areas marked B and C are similar to the areas
marked D and A, respectively, the core 54d then playing a similar role to
that of the window 54c. Since the subsequent steps enabling the finished
part 90 to be obtained are consequently similar to those already
described, they will not be explained again.
As shown in FIG. 11, the finished part 90 has a visible face 94 and
comprises a plastics material support part 92 covered by the decorative
foil 53 on the portion 90b of the part, which surrounds the non-covered
portion 90a and is surrounded by the non-covered portion 90c.
FIGS. 14 to 16 illustrate a variant for producing an aperture in a foil. In
these figures a mould 104 comprises a fixed part 104b and a movable part
104a, between which is formed a moulding cavity 117. The two mould parts
are at least partially closed. A foil 102 is disposed between these two
mould parts and in particular in the mould cavity 117.
An anvil 107a is disposed inside the movable part 104a and delimits the
moulding cavity 117 therein. A hammer 107b comprising a cutting part 107d
is disposed inside the fixed part 104b, at the boundary of the moulding
cavity 117 and opposite the anvil 107a. The hammer 107b slides relative to
the fixed part 104b. In order to reduce the wear of the fixed part 104b, a
plunger 107c is placed between the fixed part 104b and the hammer 107b.
The assembly formed by the hammer 107b and the anvil 107a forms a punch
device, that is, the moving together of the hammer 107b and the anvil 107a
brings about the cutting of the foil 102 when it is disposed therebetween.
The foil continuously separates the moulding cavity 117 into a first cavity
116, at the boundary of which the hammer 107b is disposed, and a second
cavity 118 at the boundary of which the anvil 107a is disposed.
In FIG. 15 the bringing into contact of the projecting part 107d of the
hammer 107b and the anvil 107a produces an aperture 102a (illustrated in
FIG. 16) in the foil 102 so that the spaces 16 and 18 are immediately
placed in fluid communication. This aperture surrounds a blocked-out area
102b of the foil. The contact between the hammer and the anvil is
advantageously brought about along a discontinuous line. Consequently, the
cut-out is discontinuous and produces an aperture 102a formed by a
plurality of passages through the foil 102. However, the cut-out could
also be continuous.
As shown in FIG. 16, the hammer 107b and the anvil 107a are then held in
contact with each other whilst plastics material 101 is injected into the
spaces 116 and 118 and until the part cools. Thus there is no plastics
material 101 opposite or on either side of the blocked-out area 102b of
the foil.
After cooling, it is easy to remove the blocked-out area 102b of the foil,
so creating a continuous passage (hole) 146 from one side to the other of
the finished part 140, illustrated in FIG. 17. The edge of this passage
has a good appearance on the side with the visible face 144 since it has
the appearance of a collar 148 of plastics material concealing the cut-out
in the foil.
As a variant, it is possible to offset or move the anvil 107a and the
hammer 107b when the foil has been cut out so that they enable the
blocked-out area 102b to be immersed in the plastics material. This
produces a finished part composed of a moulded-over portion and a
non-moulded-over portion which has no passage therethrough.
It will be appreciated that the invention can produce the finished part
shown in FIG. 18 since it differs from the part shown in FIG. 17 only in
that the passage 146 is formed at the edge of the finished part.
FIG. 19 shows the visible face of the part 40 of FIG. 1, the decorative
foil 2 being completely surrounded by the non-covered portion of the
support 42.
FIG. 20 illustrates a variant of FIG. 19 which can also be produced by the
process according to the invention. The covered and uncovered portions are
adjacent here.
FIG. 21 shows a part comprising a support part 42 which is not covered and
a part which is covered by a decorative foil 2. The covered part has a
passage 146 surrounded by a collar 148 made of plastics material and
produced on the visible face 144. To a certain extent, this is a
combination of the illustrations of FIGS. 17 and 20.
FIG. 22 shows the visible face 94 of the finished part 90 of FIG. 11. The
decorative foil 53 surrounds a non-covered portion of the support 42 and
is surrounded by a further non-covered portion of the support.
It will be appreciated that the invention is in no way restricted to the
embodiments described above. Thus, the window could be structurally
connected to the movable part of the mould, without thereby modifying the
process for producing the finished part. In particular, the window and the
fixed part of the mould could be operatively connected.
The foil could also be preshaped in order to impart thereto greater
rigidity and/or an initial shape which facilitates the positioning of the
foil in the mould--cf. in particular GB-A-2 271 956--for example by
interlocking.
Top